Octave and separate toolchain

Building of octave together with a separate toolchain (custom built gcc/binutils/...).

This is required mainly when the base linux distribution ships too old a version of gcc.
Unexperienced users should upgrade their distribution, though.

The main build directory will be called /usr/local/build.
It was first created by root, and then changed to be owned by the user who will perform compilations.
You might want change this to another directory in your $HOME for instance.